Determination of the More Adequate Modified Agglutination Test Cut‐off for Serodiagnosis of Toxoplasma gondii Infection in Sheep

Toxoplasmosis is one of the most common food borne disease world‐wide. Among food animals, sheep seems to having higher prevalence of Toxoplasma gondii infection. However, there is no consensus about the best cut‐off for serodiagnosis in sheep. To estimate the more adequate cut‐off value of Modified Agglutination Test (MAT) for serodiagnosis in sheep, a commercial ELISA kit was used as a golden standard. Evaluation of the optimal sensitivity and specificity was calculated using Youden’s J‐statistics. Values obtained were used to estimate the prevalence of sheep toxoplasmosis. One thousand four hundred and sixty seven blood samples were collected randomly from 160 farms from northern Portugal, representing approximately 10% of the ovine population from the region. All sera were tested for anti‐T. gondii antibodies using the MAT. One hundred nine sheep (7.4%) presented a MAT titer ≥1 : 80; 45 (3.0%) a MAT titer of 1 : 40; 97 (6.6%) a MAT titer of 1 : 20 and 1216 (83.0%) a MAT titer ≤1 : 20. The best Youden’s J‐statistic was obtained at 1 : 20 titer (0.752), with 86.15% of sensitivity and 89.09% of specificity with negative and positive predictive values of 90.32% and 84.48% respectively, suggesting that the 1 : 20 was the most appropriate cut‐off for serodiagnosis of toxoplasmosis in sheep. Assuming this cut‐off, the prevalence of toxoplasmosis in the studied population was 17.1% and 92 (57.5%) of the 160 studied flocks having one or more positive sheep. Those results indicate that toxoplasmosis in Portugal should be considered in the differential diagnosis of abortions in sheep and neurological signs in lambs. Furthermore, while Portugal produces ovine meat for internal consumption and for exportation, isolation of T. gondii from ovine meat and further characterization of the isolates will be needed to understand the risk that ovine toxoplasmosis may represent for human health.     

GnRHa‐induced Multiple Spawns and Volition Spawning of Captive Spotted Rose Snapper,Lutjanus guttatus,at Mazatlan,Mexico

Sexual maturation and induced spawning treatments were carried out with captive spotted rose snapper, Lutjanus guttatus. A total of 3013 × 10⁶ eggs (64.7% were floating) were produced from eight treated females in 42 spawns induced with GnRHa implants during the course of the present study. GnRHa ethylene‐vinyl acetate copolymer effective doses were 204 ± 11 µg/kg in June 2005, and 224 ± 13 µg/kg in July 2005. General fertilization was 50.9 ± 34.5% and 12–14 h after spawning, viability of floating eggs was 90.4 ± 12.4%. Mean incubation period at 29–31 C was 18–20 h, and mean hatching was 94.4 ± 8.2% (73–100%). Newly hatched larvae were 2.18 ± 0.15 mm in total length (TL). One month after the last hormone experiment, previously GnRHa‐treated and untreated fish began spawning voluntarily. Hormone‐treated breeders had higher fecundity than untreated fish, producing 72.5 million eggs versus 13.9 million eggs for the untreated fish, over the following 11 mo. Combined data of volitional spawning for total egg fertilization, viability, hatching, and larval TL were 77.7 ± 1.8%, 90.3 ± 1.3%, 87.9 ± 2%, and 2.50 ± 0.12 mm, respectively. These results can ensure the sustainability of a commercial hatchery.     

Potential use of a Yersinia ruckeri O1 auxotrophic aroA mutant as a live attenuated vaccine

The aroA gene of Yersinia ruckeri, which encodes 5-enolpyruvylshikimate 3-phosphate synthase, was insertionally inactivated with a DNA fragment containing a kanamycin resistance determinant and reintroduced by allelic exchange into the chromosome of Y. ruckeri 21102 O1 by means of the suicide vector pIVET8. The Y. ruckeri aroA::Kan(r) mutant was highly attenuated when inoculated intraperitoneally into rainbow trout, with a 50% lethal dose of >5 x 10(7) CFU. The mutants were not recoverable from the internal organs 48 h post-inoculation or later. The vaccination of rainbow trout with the AroA mutant as a live vaccine conferred significant protection (relative percentage survival = 90%) against the pathogenic wild-type strain of Y. ruckeri.     

Stones and Organic Mulches Improve the Quercus Ilex L. Afforestation Success Under Mediterranean Climatic Conditions

This work studies the influence of two mulching treatments on soil properties and the field performance of afforested holm‐oak seedlings (Quercus ilex L. subsp. ballota (Desf.) Samp.) nine years after outplanting. Mulching treatments composed of stones, forest debris, and an untreated control were randomly applied to 180 seedlings (n = 60) in January 2001 at the bed level (1 × 1 m) in an abandoned agricultural field in SE Spain. Survival, growth measured by means of leaf area, and nutrient concentrations in leaves and soil were measured. Both mulches provided higher survival and greater leaf‐area growth than the control, but did not differ in leaf‐nutrient concentration. Most of the analysed soil variables were not affected by the mulching treatments at the end of the study period, and, therefore, the soil properties changes by mulching might be slower than expected under semi‐arid conditions. Copyright © 2013 John Wiley & Sons, Ltd.